Page images
PDF
EPUB

Wallach, L.; Grube, J.W.; Madden, P.A.; and Breed,
W. Portrayals of alcohol on prime-time televi-
sion. J Stud Alcohol 51(5):428–437, 1990.
Wills, T.A. Stress, coping, and tobacco and alcohol
use in early adolescence. In: Shiffman, S., and
Wills, T.A., eds. Coping and Substance Use.
San Diego, Calif.: Academic Press, 1985.
Pp. 63-94.

Windle, M. A longitudinal study of antisocial behaviors in early adolescence as predictors of late adolescent substance use: Gender and ethnic group differences. J Abnorm Psychol 99(1):86– 91, 1990.

Windle, M. Alcohol use and abuse: Some findings from the National Adolescent Student Health Survey. Alcohol Health Res World 15(1):5–10, 1991.

Wylie, A.; Casswell, S.; and Stewart, J. The response of New Zealand boys to corporate and

sponsorship alcohol advertising on television. Br J Addict 84(6):639–646, 1989. Zucker, R.A. The four alcoholisms: A developmental account of the etiologic process. In: Rivers, P.C., ed. Nebraska Symposium on Motivation. Vol. 34. Alcohol and Addictive Behavior. Lincoln, Nebr.: University of Nebraska Press, 1986. pp. 27-83.

Zucker, R.A. Alcohol involvement over the lifespan: A developmental perspective on theory and course. In: Gaines, L.S., and Brooks, P.H., eds. Alcohol Studies: A Lifespan Perspective. New York: Springer, in press.

Zucker, R.A., and Fitzgerald, H.E. Early developmental factors and risk for alcohol problems. Alcohol Health Res World 15(1):18-24, 1991. Zucker, R.A., and Gomberg, E.S.L. Etiology of alcoholism reconsidered: The case for a biopsychosocial process. Am Psychol 41(7):783–793, 1986.

SECTION

III

CONSEQUENCES OF ALCOHOLISM, ALCOHOL USE AND ABUSE

CHAPTER

7

BIOCHEMICAL EFFECTS OF ALCOHOL METABOLISM

Introduction

I

n science, the term alcohol refers to compounds that have a hydroxyl group, i.e., an oxygen and a hydrogen (-OH) bonded to a carbon molecule. As a class of compounds, alcohols abound in nature and have numerous physiological, pharmaceutical, industrial, and commercial applications. Some common alcohols include ethanol, which occurs naturally as a fermentation product of sugars and grains and is consumed as a beverage; methanol, an industrial solvent also known as wood alcohol; ethylene glycol, an antifreeze; menthol, a fragrant and flavoring agent isolated from peppermint oil; isopropyl alcohol, used primarily as a rubbing alcohol; and cholesterol, an important component of tissues and a precursor of many steroid hormones that are also alcohols.

The ubiquitous and diverse nature of alcohols most likely led to the development of enzymes with the ability to eliminate and extract energy from these potentially toxic substances. The primary enzymes that metabolize alcohols, the alcohol dehydrogenases, are found in a variety of living organisms, including bacteria, yeast, plants, reptiles, and mammals. Alcohol dehydrogenases are present in human tissue and play a role in the web of metabolism. Their primary function is to oxidize alcohols to other compounds known as aldehydes and ketones, and often to catalyze the reverse, the reduction of aldehydes and ketones to alcohols. Ethanol ingestion perturbs this natural process and other metabolic processes. These perturbations may

produce a variety of clinical complications, including tissue damage, malnutrition, and weight loss.

Human alcohol metabolism will be described first in this chapter. This section will be followed by a discussion of the effect of ethanol ingestion on this and other metabolic processes.

Beverage alcohol-which is known chemically as ethanol is absorbed from the stomach and intestinal tract into the circulatory system and transported to the liver for metabolism; it also may be metabolized in the stomach.

Human Alcohol Metabolism

Beverage alcohol-which is known chemically as ethanol-is absorbed from the stomach and intestinal tract into the circulatory system and transported to the liver for metabolism; it also may be metabolized in the stomach. The first step in the metabolism of ethanol involves conversion of ethanol to acetaldehyde by alcohol dehydrogenase (figure 1). Acetaldehyde, in turn, is oxidized by another enzyme, aldehyde dehydrogenase (ALDH), to produce acetic acid. Each of these steps produces one molecule of the reduced form of nicotinamide adenine dinucleotide (NADH) from the oxidized form, NAD*. In these reactions, NAD* serves as a coenzyme,

« PreviousContinue »